This invention relates generally to an electrophotographic printing machine, and more particularly concerns an improved stapling apparatus for use therein.
In the process of electrophotographic printing, a photoconductive member is charged to a substantially uniform level sensitizing the surface thereof. The sensitized photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the sensitized photoconductive surface selectively discharges the charge in the irradiated areas to record an electrostatic latent image on the photoconductive surface corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed by bringing a developer mix into contact therewith. Generally, the developer mix comprises carrier granules having toner particles adhering triboelectrically thereto. The greater attractive force of the electrostatic latent image causes the toner particles to be attracted from the carrier granules to the latent image. Thereafter, the toner powder image is transferred from the photoconductive surface to a copy sheet and permanently affixed thereto. This general approach was disclosed by Carlson in U.S. Pat. No. 2,297,691 and has been further amplified and described by many related patents in the art.
On many occasions, it is desirable to reproduce a set of original documents. Thus, it may be highly advantageous to produce a plurality of sets of copies with each set corresponding to the set of original documents. In an electrophotographic printing machine, a plurality of sets of copies may be formed by utilizing a recirculating document handling system in association with the printing machine. The recirculating document handling system is located on the exposure platen of the printing machine and advances successive original documents thereto. Each original document disposed on the platen is reproduced. After being copied, the original document is returned to the stack thereof so that it may be re-imaged for the next successive copying cycle. In this manner, collated sets of copies are formed. Frequently, the set of copy sheets are automatically stapled together. In high speed electrophotographic printing machines, it is highly desirable to minimize machine down time due to the stapler malfunctions. One type of stapler malfunction is the jamming of a staple in the throat or passageway thereof during the drive stroke. The causes of such jams are varied and principal among them is the occasional type wherein the legs of the staple move rearwardly into the passage as the crown is moved downwardly during the driving movement either because the legs do not properly enter into the drive track or they are somehow deflected rearwardly during the driving action. Another type of jamming occurs when the staple crown enters the guide track in a horizontally canted relation so a part adjacent one leg extends into the track and another part adjacent the other leg is still supported by the staple magazine. As the staple decends, the crown may be deformed into wedging engagement with the track with a portion thereof still being within the magazine. In any case, the removal of a jammed staple from the stapler head in a readily simple manner by the operator with a minimum amount of time expended therefor is highly desirable.
Accordingly, it is a primary object of the present invention to improve the jam clearance mechanism of a stapling apparatus employed in an electrophotographic printing machine.